1. Field of the Invention
The present invention relates to a speaker system for motor vehicles, and more particularly to a speaker system equipped with an alarm device.
2. Description of Background Information
Various types of speaker systems are used in car-stereo systems. Flush-type speaker systems and on-the-shelf speaker systems are examples of such speaker systems. The flush type speaker systems are mounted in doors, or in the rear-window shelf of an automobile in such a manner that an opening having the size and shape for receiving a speaker (speaker unit or driver) of the speaker system is formed in an inside board of the door or in the rear-window shelf, and the speaker is fitted therein. In order to fix the speaker to the door or the rear-window shelf, screws provided at the peripheral part of a frame of the speaker, for example, are used. On the other hand, the on-the-shelf type speaker system has an enclosure (or a cabinet) in which one or more speaker is mechanically supported. In order to fix this on-the-shelf type speaker system on the rear-window shelf, screws provided at the bottom of the enclosure are generally used, in such a manner that the rear-window shelf is sandwiched between the bottom of the enclosure and an iron plate situated underneath the rear-window shelf, forming a part of the car body.
The above described method are generally employed for mounting speaker systems in a motor vehicle. However, since removal is as easy as the mounting in the case of the above method, stealing of speaker systems becomes frequently committed.
Moreover, since the vibration is inevitably generated while the motor vehicle is running, there also is a problem of loosening of the screws used for mounting the speakers or the speaker systems. In the event that the screws are loosened, the quality of sound generated by the speaker will be degraded. Furthermore rattling noises may be generated by the friction between the speaker system and the supporting part such as the rear-window shelf.